As integrated circuits have become smaller and smaller in recent years, down to the sub-micron level, there has been a growth in the number of fabrication defects. Such defects arise because of variations in masks and materials during the fabrication stage. This has created the need for reliable testing and diagnosis of complex integrated circuits.
Security and reliability of integrated circuits is a field of research which has garnered attention over the past ten years. To maintain safety using security, an encrypted core is needed that is capable of withstanding physical and side-channel attacks that take advantage of physical mounting. At the same time, Trojan horses, which embed malicious circuits during the fabrication stage, have also received attention. Security and reliability can become performance indicators to be inspected pre-shipment in products where security is key.
In the technical field of hardware security, processing is left to an embedded encrypted core in applications where security is vital in complex system-on-chip (SoC) configurations. However, security cannot be guaranteed simply by embedding an encrypted core. In order to declare a device secure, it has to be tested against various threats and policies. One example of a threat is a side-channel attack (SCA) (see for example Non-Patent Literature 1, 2, and 5). Side-channel attacks are carried out by abusing information unintentionally radiated from a physical device, such as power consumption, electromagnetic wave radiation, processing time, and so on.
The theory and implementation of side-channel attacks have been widely discussed at academic conferences, but no standard measurement environment has been described for analyzing such attacks. The most common method for measuring power consumption is the low-resistance method, whereby a resistor of around 1 Ω is inserted between the ground (GND) pin and the ground (GND) of the semiconductor chip. This technique is also called a low-side technique (see, for example, Non-Patent Literature 5). A high-side technique has also been proposed for the power, in which a weak resistor is placed between the power voltage (Vcc) pin and the power voltage (Vcc) of the semiconductor chip. Both measurement methods have low implementation costs but also disadvantages. The low signal level is a problem in low-side techniques, while the exposure to significant power source noise from the power supply is a problem for high-side techniques. This means a low SNR (signal-to-noise ratio) in both cases. The resistors that are inserted act like low-pass filters, suppressing high-frequency components in the signal.
Electromagnetic (EM) probes are also used as a way to carry out high-precision side-channel attacks (see, for example, Non-Patent Literature 6). Measurement using electromagnetic probes can be done with little noise, but this depends on the measurement location. The measurement band of electromagnetic probes is several GHz, which is broader than low-resistance techniques.